Yellowstone’s Prehistoric Bison:A Comment on Keigley (2019)

By Robert L. Beschta and William J. Ripple

On the Ground• We provide additional information addressing theissue of whether American bison (Bison bison) weregenerally absent or present in Yellowstone NationalPark prior to its establishment in 1872.

• Our results support Keigley’s conclusion that bisonherds before the mid-1800s were absent inYellowstone National park, and particularly thepark’s northern range.

• Our results also support Keigley’s conclusion thatbison had no significant role in the ecologicalprocesses that helped shape the park’s originallandscape.

Keywords: bison, Yellowstone National Park, NativeAmericans, market hunting.

Rangelands 41(3):149—151doi 10.1016/j.rala.2019.03.002© 2019 The Society for Range Management.

eigley undertook an analysis and synthesis ofseveral lines of evidence, including archeological

K information, Native American practices, andearly Euro-American reports, to assess the

potential presence of bison (Bison bison) in the area thatwas eventually to become Yellowstone National Park(YNP).1 Overall, he found this “array of evidence” indicatedbison herds were absent in YNP before the mid-1800s.Herein we provide additional information on the presenceand absence of bison prior to the 1872 establishment ofYNP, with particular emphasis regarding the park’snorthern ungulate winter range, or “northern range,” aswell as its Lamar Valley. Currently as many as 4,000+ bison,well above historical population norms for the park, utilizeYNP’s northern range throughout the year. And, in thenorthern range’s Lamar Valley, high bison densities havehad major impacts to soils, riparian and wetland vegetation,and stream and river channels (Fig. 1).2–5

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Gates and Broberg indicated that humans utilizedYellowstone from the early Holocene until about 3,000 to1,500 years before present, after which the abundance ofarcheological material diminished coincidentally with theLittle Ice Age (ca. 1450 to 1850).6 Increased climate severityduring the Little Ice Age likely reduced ungulate populationsin mountainous areas and may explain the diminishedarcheological material during that period. Deep snowaccumulations in mountainous areas can significantly affectforage availability for grazing animals and these patterns oftenstrongly correlate with migration to lower elevations.6 Ifsevere winters were a common occurrence during the Little IceAge, it would seem unlikely that bison would have over-wintered in mountainous areas such as those represented byYellowstone’s northern range.

The journals of Osborne Russell in the 1830s provided theearliest Euro-American observations of bison abundance anddistributions in the YNP area. Keigley’s review of thosejournals indicated that reports of bison were frequent for areasoutside the park; however, there was not a single reporting ofbison inside the park, a contrast suggesting an absence ofbison in YNP.1 In the 1830s, as well as previous decades,Sheepeaters (Shoshone speaking Native Americans) were theprimary occupants of the area that eventually was to becomeYNP and its surrounding areas. In summer they went highinto the mountains in pursuit of “mountain sheep” (i.e.,bighorn sheep; Ovis canadensis), whereas in winter they settledalong sheltered creek or river bottoms with access to “elk,sheep, deer or even bison” (p. 46).7 Janetski reported thatRussell found the Sheepeaters in the Lamar Valley to be“neatly clothed in dressed deer and sheep skin” (p. 40).7 It wasfurther noted that because of the quality of their tanned deer,elk, and sheep skins, the Sheepeaters were “able to trade themto Plains groups for buffalo robes” (p. 48).7 Theseobservations provide additional merit to a conclusion thatthere was a general absence of bison inside the park in theearly 1800s.

Following the extermination of bison herds on the SnakeRiver Plains, Keigley indicates Bannocks and Shoshone beganto regularly traverse the park, across the current-day northernrange and specifically through the Lamar Valley, on their way

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Figure 1. Example of ongoing impacts by bison to Rose Creek in the Lamar Valley where compaction and trampling by historically high numbers arecontributing to streambank collapse, as well as channel widening and incision. In addition, intensive bison herbivory is preventing establishment and growthof riparian plant communities (e.g., willows, cottonwoods, sedges), thus preventing them from providing root strength (bank stability), litter and insect inputsto the stream, and shade from vegetation canopies that mediates water temperature.

to buffalo grounds on the plains in southeastern Montana.1

These transits of the park apparently occurred from ~1840until the late 1870s.7 It seems doubtful that Bannocks andShoshone would have consistently journeyed to the east side ofthe Rocky Mountains in search of bison had there beensignificant numbers of these ungulates present within thepark’s northern range.

Kay undertook a compilation of wildlife observations from thejournals of early trappers and explorers where he “systematicallyrecorded all observations of ungulates and other large mammalsfound in 20 first-person historical accounts of exploration in theYellowstone area from 1835 to 1876” (p. 251).8 He evaluated atotal of 765 observation days. Within the Greater YellowstoneEcosystem, bison composed 3% or less of the total number ofungulates reported in these journals as “seen” or “killed.”Based onthe reported relative scarcity of both ungulates and largecarnivores, Kay concluded that “ungulates were not historicallyabundant in and around Yellowstone National Park” and that“bison were rare” (p. 288).8

In another assessment of wildlife occurrence and abun-dance in and around the park, Schullery and Whittleseysynthesized observations and reports from between 1806 and1881.9 Although bison, sometimes in large numbers, wereoccasionally witnessed at lower elevations outside the park inearly reports, any bison inside the park were infrequentlyreported up until about 1870 and there were no specificreports identifying bison herds in or near the northern range’sLamar Valley prior to 1870. However, starting in the early1870s the occurrence of reported bison in the park becamemore common and bison herds of several hundred or more

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were sometimes observed. P. Norris, who later would becomethe park’s first superintendent, reported in 1880 there wereabout 600 bison in the park, consisting of three herds.9 Thisapparent increase in park bison during the 1870s occurred at atime when bison on the Great Plains were approachingextermination due to market hunting.10 Heller indicated thatbison in the early years of the park had been largely “derivedfrom the original remnant of our great western herd” andowed their preservation to the fact that they consisted of“individuals which voluntarily or under pressure from thehunters on the plains chose to winter in the Yellowstone Parkregion” (p. 458).11

The age structure of long-lived woody species providesanother perspective of ungulate populations in the 1800s. Forexample, from 1800 through the early 1900s there was a trendof an increasing number of cottonwoods (Populus spp.) perdecade in the Lamar Valley, indicating that ungulate levelsduring that period were not sufficiently high to prevent theestablishment of cottonwood trees.12 The resultant “j-shapedcurve” for number of cottonwood trees vs. decade representedan expected relationship where young cottonwoods had, overtime, been able to consistently grow above the browse level ofungulates. Thus, even if bison or other ungulates utilized thenorthern range during the 1800s, their numbers weresufficiently low that a continuous recruitment of cottonwoodswas able to occur.

Yellowstone’s bison have been managed by the ParkService since the early 1900s and these practices shed furtherlight on the issue of seasonal migration patterns that mighthave occurred prior to park establishment. From 1902 to

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1952 northern range bison were fed hay inside the park everywinter, and from 1913 to 1932 nearly 7 km of woven wirefence were maintained along the northern boundary of YNPto prevent bison and other ungulates from leaving the park.13

After bison culling inside the park was stopped in 1968, apolicy of boundary control was adopted by the Park Service toprevent them from leaving the park, a policy that variouslyincluded hazing to keep them inside and, in some cases, theshooting of bison that approached the boundary.14 Thus, theextent to which winter weather and snowpack accumulationsmight normally drive bison to lower elevations and eventuallyout of the park has generally been thwarted by Park Servicemanagement practices over the last century. That thesevarious practices (i.e., supplemental winter feeding, boundaryfences, and hazing) have been a long-term component ofbison management strongly suggests that the northern rangewas not a preferred wintering ground for bison.

We are unaware of any journal or historical accountconfirming the occurrence of bison herds on the northernrange before the 1870s. Furthermore, the climatic conditionsof the Little Ice Age and associated archeological data,observations about Lamar Valley Sheepeaters’ clothing, use ofthe park’s northern range as a route by Shoshone-Bannocks toobtain bison in eastern Montana, and a continuous record ofcottonwood recruitment in the Lamar Valley during the 1800sprovide additional insights and indicate an absence ofsignificant bison numbers prior to park establishment.Collectively, these various lines of evidence are supportive ofKeigley’s conclusions that 1) bison herds were absent beforethe mid-1800s, and 2) they had “no significant role in theecological processes that shaped YNPs prehistoric landscape”(p. 1).1

AcknowledgmentsThis work was supported in part by National Science

Foundation Grant 1754221. We are appreciative of construc-tive comments from two reviewers.

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